Method of and apparatus for pulverizing frangible substances.



G. A. ovERsTRoM. METHOD 0F AND'PPARATUS FO PULVERIZFNG FRANGIBLE SUBSTANCES.

APPLICATION FILED AUGJI. |916.l

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G. AQOVERSTROM. METHOD 0F AND APPARATUS FOR PALLVERIZING FRANGIBLE SUBSTANCES. APPLICATION guru Auml. |916.

1,300, 192. Patented Apr. 8,1919.

2 SHEETS-SHEET 2.

an if a y v aI 17H/enfer.' i @Ud/We A Ure/61mm GUSTAVE A. OVERSTROM, F PASADENA, CALIFORNIA.

METHOD 0F AND APPARATUS FOR PULVERIZING FRANGIBLE SUBSTANCES.

Specification of Letters Patent.

Patented Apr. s, 1919.

Application led August 21, 1916. Serial No. 115,947.

To all Iwhomz't may concern Be it known that I, GUsTavE A. OVER-- sTRoM, a citizen of the United States of America, residing at Pasadena, in the county of Los Angeles and State of California, have invented a new and useful Method of and Apparatus for Pulverizing Frangible Substances, of which the following is a specification.

This invention relates t0 the art of pulverizing ore, rock or similar material, and particulaily to improvements in the method and apparatus wherein the ore is pulverized by being thrown from an impeller, rotating at high speed and caused to strike an obstructing surface at such high velocity as to break the ore or rock by the force of the impact. An important object of the invention is to utilize the material which is being subjected to the centrifugal operation to form a protective surface for the impeller body and to form an abrading means for assisting in pulverizing the material.v For this purpose l provide for retaining a ybed or body of such material on or within the impeller in such manner `that the impact and abrasion due to passage of the material over or through the impeller are taken by such bed or body which thus protects the iinpeller from wear and at Athe same time assists in the comminution of the material.

Another object of the invention is to provide for convenient and economical renewal of such parts as are unavoidably subject t-o wear.

Another objectl of the invention is to provide an improved construction of the die or stationary means for receiving the impact of the material when ift is thrown from the impeller, whereby it. may more effectively resist the wear due to the operation of the apparatus.

Other objects and advantages of my invention will appear hereinafter. l

The accompanying drawings illustrate an apparatus suitable for carrying out my invention, and referring thereto:

Figure l is a plan view partly in section, the impeller being shown as empty.

Fig. 2 is a vertical section, the impeller being shown as containing a bed of protective material.

Fig. 3 is a detail sectional view of the head of the impeller spindle.

Fig. 4 is a Iside elevation of the machine.

Fig. 5 is a partial side elevation of a modification.

- The invention comprises a frame, a ver-- tically extending spindle mounted in said frame, an impeller carried by said spindle, means carried by said frame for receiving the impact of the material discharged from the impeller, and means for feeding material to the impeller. The frame of the machine may be of any suitable construction, comprising, for example, a base 1, a casing 2 thereon, and an upper casing 3 mounted on tlie casing :2. An interior frame member 4 is mounted Within the casing 2, for eX- ample by means of arms 5 ,and a web 7. All of the members 2, 3 and 4 are substantially cylindrical in shape, the frame member 4 being mounted coaxially with the members 2 and 3, so as to form an annular space 6 between the inner member 4 and the outer members 2 and 3, and the frame is formed with an inclined web 7 connecting the casing 2 and the inner frame member 4, so as to form an inclined chute at the bottom of said space 6, whereby the pulverized mate-rial is conducted by gravity to a discharge opening 8 in the base 1.

Base l is provided withaFtaper seat 9 for a bearing sup ort 10, Which is tapered to lit said seat. Said support 10 supports a bearing sleeve 11 which is formed with a bearing surface for engaging the spindle 14 for the impeller, said bearingsupport 10 being provided with a ball and socket bearing for sleeve 11 and with a loWer 'bearing plate 17 engaging a member 13 on the lower end of said sleeve, the engaging faces of said plate and sleeve being rounded concentrically with the center of the ball and socket bearing, so that the spindle may gyrate on'this center. A driving pulley 19 is mounted on the spindle 14 around the bearing portion thereof, so that the lateral stress of the belt running on said pulley is substantially balanced with respect to the center of support of the spindle, and the spindle is therefore free to rock on said support. Such rocking o'r gyrating motion of the spindle on its support is resisted and controlled by resilient supporting mea'ns consisting, for example,

of spiral springs 20 arranged in an annular series around the spindle and having their inner portions connected by bolts 21 to a spider 22, provided with a bearing 24 for the spindle, and said springs having their outer portions connected to a ring 23 secured to the stationary frame member 4. The construction of this yielding support for the spindle may be substantially as shown in my application filed May 9, 1916, Serial No. 96275, for flexible bearing for high speed spindles. An impeller is mounted on the upper end of spindle 14, said impeller being preferably formed as a bowl or cup-shaped member consisting, for example, of a disk 25 secured to the upper end of spindle l14 an annular member 26 secured to the disk 25 and eX- tending upwardly therefrom, and a ring 27 secured to the annular member 26 and extending above the same to form a removable lip or rim for the bowl. The annular member 26 is preferably flared upwardly on its inside. Disk 25fis secured to the spindle by a taper fit and is held in position by wedge keys 28 in a recess 28 in said spindle and extending out into keyways 88 in the bottom member of the impeller, said keyways having inclines 88" for engaging said keys so that centrifugal action in the keys will hold the parts fast. A circular cap 29 covers the top of spindle 14, a lug 54 on the bottom thereof resting in a recess 54 in the top of the spindle, said -cap covering the `adjacent portions of the impeller bottom.

An important feature of my invention in -connection with the impeller, is the provision of means for maintaining a portion of the ore or rock in position within t'he impeller, so as to form a wearing face consisting of the ore or rock itself which takes the impact and abrasion of the ore or rock in passing through the impeller. For this purpose the walls of the impeller are so formed as to hold the ore or rock therein against the action of centrifugal force, t'he steeply inclined peripheral walls ofthe bowl shaped impeller, for example, serving to hold a bed of ore or rock in this manner, as indicated .at b, the bed or |body of ore accumulating withinv the'impeller until .its upper surface assumes the angle of repose. proper to the lmaterial being handled, as indicated by the line a-'a, in Fig. 2. To prevent relative displacement of the bed or body of ore or rock, in the impeller, during sudden acceleration or retardation of the impeller in starting or stopping, wings or blades 30 may be provided, formed as flat strips or lates extending between flanges 31 on brac ets 32 which are bolted or otherwise fastened to the bottom disk of the impeller, said brackets bein arrangedin pairs so that a spaceis left between the opposing flanges 31 0f each pair of brackets adapted to receive and fit a corresponding strip or plate l30, said strip or plate projecting beyond flanges 31 sufficiently to form wings extending inwardly into the bowl. The inner edges of these wings are preferably inclined along a line parallel to and somewhat below the line a-a above referred to, the same being a line drawn from the upper edge of the impeller bowl obliquely downward to the bottom of the bowl at or within the center thereof, the Obliquity of this line being substantially that represented -by the angle of repose, the inclination of the bed or body of pulverized material in the bowl under the coinbined action of gravity and centrifugal force at.

normal speed of the machine, so that the upper edge of the blades or wings 30 will be slightly below the surface of the bed or body of pulverized material in the impeller bowl, andthe wings or plates will therefore be protected by said body of ore or rock, while at the Same time being embedded in and engaging such body of ore or rock in such manner as to cause the ore or rock to move rotatively with the impeller bowl. The blades or wings provide transverse pockets on the peripheral wall.

A die or impact receiving member is provided on to of the frame member 3, and around the 11p of the impeller bowl, prefera'bly comprising a plurality of annular members arranged one above another, each annularmember preferably being built up of a plurality of sections vor segments 34 of chilled steel, white iron, or other suitable material. Each of these segments is preferably formed with teeth o1' projections 35 extending inwardly toward the center of the machine All of the said series of segments are maintained withina frame oi` retaining ring 36, and for convenience in construction and operation this ring is preferably provided with upper and lower annular flanges 37 and 38, each of which is provided with means for engaging the top of the frame member 3 so that the ring may be reversed as a whole if desired. For this purpose, each of the flanges 37 and 38 may be provided with an annular rib 41 adapted to engage in an annular rabbet 40 on the top of frame 3, the construction being such that the entire member consisting of ring 36 and annular flanges 37 and 38 wit'h the segments 34 carried thereby, can be turned around the axis of the machine to shift the point of greatest'wear on the segments 34, as may be found necessary. vIn case of a small mac'hine, this .rotative movement of the parts aforesaid may be effected by a capstan bar `inserted in holes 56 in studs 49 or in case of a large machine, this may be effected by gearing, the annular flanges 37 and 38 being provided in that case with gear teeth, indicated at 39 and a pinion 42 being mounted on a shaft 43 journaled in a bearing 44 on the frame member 3 and provided with an operating handle 45, said pinion being adapted to engage the gear teeth on the i lower annular flange aforesaid to rotate the lower edges of ring 36, these members 37, 36

and 38 being clamped together, to form a rigid body, by means of bolts 47. Said body may be held rigidly` in position on frame member 3 by eyebolts 48 having eyes engaging studs 49 on ring 36, said bolts extending between lugs 50 on frame member `3 and being secured by nuts 51 on said bolts and engaging said lugs.

Suitable feed means are provided for the machine, comprising for example a hopper or funnel 52 carried by a top member 53 resting on top of the upper annular flange 37, said hopper or funnel having a removable mouthpiece 63 whose discharge opening extends centrally within the impeller bowl above described, so as to conduct the material to be pulverized, into the bowl below the discharge lip thereof, said mouthpiece having a flange 53 resting on a shoulder 52 on funnel 52. Any suitable means may be provided for oiling the spindle and its bearings. For example z-As shown in Fig. 2, the spindle 14 may be provided with an axial bore 55, extending from its lower end to 4near the upper end of the spindle and provided with openings 57, through which oil may be discharged to the outside of the shaft within the upper and lower bearings therefor, and a screw 58 is provided within this bore for forcing oil upwardly by the rotation of the spindle. An oil well or reservoir 59 is formed in the lower frame member or casing 2, suitable means, such as openings 59 closed by caps 60, being provided within the wall of said casing for supplying such reservoir with oil.' A duct 61 leads from a portion of such reservoir to a cha1nber 62 in the base 1 directly underneath the bearing support 10 aforesaid, said bearing support being provided with a passage 64 communicating with a passage 65 which extends through the bottom bearing plate 17 aforesaid, so as to communicate with an opening in the bottom of the spindle. A duct 66 in the side of the bearing support 10 for the lower bearing opens into an annu.- lar passage 67 communicating through a passage 68 with the oil well or reservoir aforesaid. The inner casing 4 is provided with an annular trough 70 and with an inclined annular apron 71 extending inwardly from the upper edge of said trough, and spindle 14 is provided with an oil shedding collar 72 abovesaid apron so that any oil running down from the upper bearing into receiving means.

said trough will pass through a pipe 73, a sight-feed device 74 and a pipe 75 to the oil well or reservoir aforesai My invention is not limited to any special form of bearing for the machine. I prefer 70 however, for convenience of construction and efficiency in operation to use, for the lower bearing, the form shown in Fig. 2 of the drawing and comprising the bearing sleeve 11 formed with a bearing in which the spindle 14 rotates and provided exteriorly with the rounded portion 11 formed as a zone of a sphere and fitting within the concave spherical bearing 15 formed on the supporting member 10 and on a sleeve 75 screwed on said supporting member and extending upwardly therefrom. Said bearing further comprises a bottom member 13 formed as a cup, resting on the bottom plate 17 aforesaid inclosing a series of superposed -disks 78 and 79, said disks being conical and alternately convexly and concavely faced, so as to centralize themselves under the vertical pressure of the spindle. A foot or step member 80, formed as a hollow taper plug, lits in a corresponding socket 81 in the lower end'l'of the spindle 14, and engages by a concave face at its lower end, the top of the uppermost disk 78, said plug having a pas sage 82 communicating at its upper end with the bore 55 in the spindle and at its lower end through passages 85 in the disks 79 and 78 and through passage 86 in the bottom member 13 with the opening .65 aforesaid, in the bottom .plate 17.

In the operation of the machine, the spindle 14 is rotated rapidly by power applied to pulley 19, and ore is fed to the impeller through hopper 52, the mouthpiece of which delivers the ore or rock into'the impeller 105 bowl below the upper edge or rim thereof. The material such as ore or rock accumulates in the impeller until it fills against the side wall thereof sulllciently to cause any further amount of material to ride over the surface 110 of the material already accumulated and to be discharged from the impeller at the `upper edge or rim of the impeller bowl.

The material thus discharged from the impeller moves tangentially with about 75% 115 of the full peripheral velocity of the im-` peller, and strikes the die means 34, so as to be pulverized or broken by impact.` The pulverized pieces Vdescend by gravity through the space 6 within the casings 3 and 120 2 and through the openin 8 to any Asuitable It will ge understood that the bed or body of material in the impeller is in general being continually worn or carried` away and continually built up or renewed inthe operation of the machine, but its general shape and effect will be maintained at all times. In starting or. stopping themachine there is a tendency of the material to swirl backward or forward rela- `material extending over the same.

wear is the rim member 27, which, being shrunk on, may be renewed whenever necessar 15171 general the material fed to the machine, for example from an overlying feeder, will tend to fall into a more or less definite part of the impeller, and will consequently be discharged therefrom so as to strike a more or less definite part of the die. This results in execessive wear at such part of the die, and in order to obviate this without the necessity of stopping the machine for replacement or shifting of the die parts, the die may be rotated fromtime to time, by means of a capstan bar placed in one of the holes 56 in the studs 49 on the retaining ring 36 for the die means, or by operation of gear means 39 by pinion 42 operated by handle or crank 45, so as to bring a. different portion of the die means into position to receive the greater wearing action. Eventually the die means will be worn so as to be concave along its inner face, by reason of the. greater wearing action near the plane of the upper edge of the impeller, from which the material 1s discharged, and this condition maybe corrected by removing the upper clamping member 38 and rearranging the die sections 34, so that the sections that were on the top. and bottom rows will be brought into the middle rows, and vice versa. The die ring may also be reversed or inverted asa whole, when desired in case of unequal wear on the upper andl ylower parts thereof or of any of the die sections. It will be understood that the resilient bearing support for the upper bearing of the spindle permits the spindle to rotate at Vthe required high speed, and to gyrate as may be* required for proper spinning action under varying conditions of load. In case of a large rock'entering the impeller it may pass under the lower edge of the mouthpiece 63 which may be lifted thereby so as not to clog the' machine.

In further explanation of the operation of the machine it may be stated that usually it is required to pulverize` a material to any given limiting size. In such a case the material is Ihandled same as in any other pulverizing device in which the screen is not a part of the pulverizer. The pulverized material drops by gravity into an elevator, onto a screen, and undersize of screen is the desired product; the oversize goes back to the hopper and enters the impeller together with the original feed. Or the pulverized material may go direct from pulverizer to screen, and oversize elevated to enter iml the force of the orlginal large pleees of rock grinding on the smaller, when all is trying to get up from a standstill to the discharge speed. The returning oversize having less mass come up to nearly the speed of the contact surface sooner than the large lumps, and the small pieces also attain a somewhat higher discharge speed than the larger lumps; hence in relation to the rotation of the bowl the larger lumps travel backward faster than the smaller. The result is that the smaller is ground by the coarser before it leaves the edge of the bowl impeller. The finer material does not accumulate enough kinetic energy' to be broken with the same relative efficiency as the coarser when it strikes the die, and for this reason a wing type of impeller is not as efficient for fine pulverizing as the bowl type here described. Rounded rocks do not attain as high a speed before leaving the edge of the bowl as flat rocks, but still the efficiency is not impaired when doing fine pulverizing as there is more backward travel of the rounded masses, hence they grind up the smaller about as well.

'The action of the rocks in the bowl is as follows: In a short while the surface of material formed in the bowl at the angle of repose becomes more or less finely pulverized up to a depth of about if the plates 30 should happen to extend out of the material they are worn down to surface of the material in a few minutes; the larger rocks become buried to some extent in the fine surface material, while they are being brought up to the speed of the surface in contact therewith, and they `move backward point about g to below the surface and this relation is from that time on maintained showing that the rocks actually plow below the surface of the material fillin the bowl. I have found that an iron owl formed to correspond with the angle of repose as given by rock material produced `vbut very little pulverizing effect as all the material slid up the iron surface so easily` that very little work was done; it is therefore necessary to make the impeller bowl less fiaring than the an le of repose for the material being pulverized. A The circumferential speed of the bowl is usually from 16000 to 17000 ft. per minute. '1 here is practically no vibration as the machine runs like a gyroscope, it is practically noiseless,

' therocks striking the die produce hardly any noise as long as rocks break; if a rock does not break the blow can be heard. The machine is very light forits capacity, power consumption and iron loss from Wear is comparatively small. It requires no special foundation and can be erected on building frames etc. If the feedfor any reason should stop, nothing happens except practically no power is consumed, so thatattendance is practically eliminated. It will do the same uniform work consuming same amount of power for the same amount of work no matter what state of wear the wearing parts .l may be in, etc.

The oil level in the well 59 is kept hig enough so that oil flows by gravity into the screw pump 58 which rotates with the spindle. In a small very fast running machine centrifugal force alone will raise the oil to the upper bearing, but in the larger and slower running machines it is necessary to augment this force by use of some pumping device such as the screw. shown.

The oil level is usually kept below the center of ball and socket or universal lower bearing, as otherwise oil may overiow from the ball-socket bearing. A

rlhe oil flows'in a continuous circulation from well 59, through passages 61,v 64 and 86 to the screw means58 the motion of which together with centrifugal action, forces the s l oil up through passage 55 and out through openings 57 into the bearings. From the upper bearing the oil runs to trough 7 0 and by pipes 73 and 75 back to the oil well.

From the lower bearing the oil runs through passages 66 and 67 back to the oil well.

In case of a small machine, the gearing for turning the die may be omitted as shown in Fig. 5, ,the construction .being otherwise as above described.

``What1 claim is:

A1. The method of pulverizing frangible substances which consists in feeding the same f upon a rotary centrifugal surface, accumulating a layer of said nsubstances by and upon said centrifugal surface, centrifugally discharging the substances and pulverizing .substances comprising a rotatable centrifugal surface provided with an upwardly extending peripheral wall having transverse pockets for accumulating` a bed of the substances thereon to receive the impact and abrasion of the substances passing over the centrifugal surface, and an annular fixed impact member surrounding and spaced apart rom the upper part of said centrifugal sur# ace. v

4. An. apparatus for pulverizing frangible substances comprising a rotatable centrifugal surface provided with an approximately flat bottom part and a -peripheral wall ex'- tending upwardly from the periphery of said fiat bottom part providing an angular construction capable of accumulating a bed of Ithe substances thereon to receive the im pact and abrasion of the substancespassing over the centrifugal surface, and an annular fixed impact member surrounding and spaced ap'art from the upper part of said centrifu gal surface.

5. An apparatus for pulverizing frangible substances comprising a rotatable centrifugal surface, a fixed frame member, a normally stationary impact receiving means adjustably mounted on said framemember, operating means for shifting said imp-act receiving means to different angular positions,

and releasable securing means for retaining said impact receiving means in any one of such different angular positions.

^In testimony whereof I have hereunto set my hand, at Los Angeles, California, this 14th day of August 1916.

GUsrAvE A. ovERs'rRoM. 

